Generally, when exhaust gases generated in vehicle engines are discharged to the outside air, noise and vibration are caused, and environmental pollution is caused. Accordingly, a catalytic converter and a muffler are installed at an exhaust passage of a vehicle, and thus occurrence of noise and vibration is minimized while blocking the discharge of environmental pollutants. At the same time, exhaust gases need to be smoothly discharged from the exhaust pipe at the end of the muffler to the outside air.
However, as shown in FIG. 2, an exhaust manifold, a catalytic converter (3) for purifying an exhaust gas, and a muffler (4) are installed on a passage from the combustion chamber of an engine (2) to the end of an exhaust pipe (9), and a flow resistance significantly acts on the discharge of an exhaust gas due to the passage (9) that has a long length. Thus, the discharge (9a) is delayed by many interferences and flow resistance while exhaust gases are passing the exhaust pipe (9), and thus the output of the vehicle engine and the fuel efficiency are reduced.
In order to over this limitation, Korean Patent Application Publication No. 10-1993-0016641 discloses an exhaust promoting apparatus on internal combustion engine. The exhaust promoting apparatus includes a diffusion pipe (1) having a trumpet shape that gradually increases in cross-section toward the end of an exhaust pipe of a vehicle, and a fluid guide member (3) disposed at an opening of the end of the exhaust pipe and gradually decreasing in cross-section in a form of surrounding the exhaust pipe. Also, a tapered induction body (2) that is narrowed in forward and backward directions is fixed at the end of the exhaust pipe by a support piece (11), and thus the outflow of exhaust gas of the exhaust pipe is promoted by air that is increased in flow velocity by the fluid guide member (30).
The exhaust promoting apparatus disclosed in Korean Patent Application Publication No. 10-1993-0016641 promotes the discharge of exhaust gas using air accelerated by the fluid guide member (3) of air. However, since a passage formed with the fluid guide member (3) is very narrow due to the diffusion pipe of the end of the exhaust pipe, accelerated air is not smoothly discharged, and thus the flow velocity of air at the end of the exhaust pipe is rapidly lowered, thereby interrupting a smooth discharge of exhaust gas.
In addition, an exhaust gas discharged from the exhaust pipe is lowered in pressure at a point where the fluid guide member (3) meets the end of the exhaust pipe and thus the discharge of exhaust gas is further induced, but in this process, the exhaust pressure of exhaust gas is reduced by a flat wall surface of the tapered induction body (2), and the discharge of exhaust gas is rather delayed.
Above all, since the point where air accelerated through the fluid guide member (3) and the end portion of exhaust gas meet each other is limited to one point, an efficiency of suctioning an exhaust gas discharged from the exhaust pipe at the end portion of the fluid guide member where the pressure is low compared to the end of the exhaust pipe is lowered.
Accordingly, a method that can discharge a larger amount of exhaust gas per unit time from the exhaust pipe using the flow velocity of external air is urgently needed.